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From "Pavel Yaskevich (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-5661) Discard pooled readers for cold data
Date Sun, 07 Jul 2013 19:19:49 GMT


Pavel Yaskevich commented on CASSANDRA-5661:

You got me wrong, I'm not trying to debate anything with you and minute details are proven
to be the hardest sometimes... I'm just trying so say, to Jonathan most of all, if we go with
borrowing approach and put cache in front of each row read we would suffer additional latency
on every read (even if it's 1-3 ms, that adds to every file read on each request) of the row
where people already report order of magnitude worse latencies on >= p99, am I right [~tjake]?

P.S. am I sorry I forgot to bow before I darred to speak up to such master who solved all
your problems and who's modesty doesn't know it's limits...
> Discard pooled readers for cold data
> ------------------------------------
>                 Key: CASSANDRA-5661
>                 URL:
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.2.1
>            Reporter: Jonathan Ellis
>            Assignee: Pavel Yaskevich
>             Fix For: 1.2.7
>         Attachments: CASSANDRA-5661.patch, DominatorTree.png, Histogram.png
> Reader pooling was introduced in CASSANDRA-4942 but pooled RandomAccessReaders are never
cleaned up until the SSTableReader is closed.  So memory use is "the worst case simultaneous
RAR we had open for this file, forever."
> We should introduce a global limit on how much memory to use for RAR, and evict old ones.

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